Bladder urothelial neoplasms in pediatric age: experience at three tertiary centers.	INTRODUCTION: Urothelial bladder neoplasms (UBN) typically occur in patients in their sixth or seventh decade of life while they are infrequent in children and young adults. They occur in 0.1-0.4% of the population in the first two decades of life. Their management is controversial and paediatric guidelines are currently unavailable. OBJECTIVE: To further expound the available data on the outcome of patients younger than 18 year old diagnosed with UBN. STUDY DESIGN: We retrospectively reviewed the files of all the consecutive paediatric patients with UBN treated in three tertiary paediatric urology units from January 1999 to July 2013. Lesions were classified according to the 2004 WHO/ISUP criteria as urothelial papillomas (UP), papillary urothelial neoplasm of low malignant potential (PUNLMP), low-grade urothelial carcinoma (LGUC), and high-grade urothelial carcinoma (HGUC). RESULTS: The table shows the results. Management after TURB varied among centres. One centre recommended only follow-up US at increasing intervals whereas another follow-up US plus urine cytologies and endoscopies, every three months in the first year, and at increasing intervals thereafter. After a median follow-up of 5 years (range 9 months-14.5 years), none of the patients showed disease recurrence or progression. DISCUSSION: UBN is an uncommon condition in children and adolescents and, unlike in adults, its incidence, follow-up and outcome still controversial. Paediatric guidelines are currently lacking and management varies among centres. Gross painless haematuria is the most common presenting symptom. Therefore, this symptom should never be underestimated. US is generally the first investigation and additional imaging seems unnecessary. TURB often allows for complete resection. Lesions are generally solitary, non-muscle invasive, and low-grade (mainly UP and PUNLMP). Ideal follow-up protocol is the most controversial point. Reportedly, recurrence or progression during follow-up is uncommon in patients under 20 years, recurrence rate 7% and a single case of progression reported so far. Accordingly, a follow-up mainly based on serial US might be considered in this age group compared to adults where also serial endoscopies and urine cytologies are recommended. In the selection of the follow-up investigations, it should also be taken into consideration that urine cytology has a low sensibility in the detection of low-grade lesions while cystoscopy in young patients requires a general anaesthesia and hospitalization, and carries an increased risk of urethral manipulation. CONCLUSION: UBN is a rare condition in children. Ultrasound is generally accurate in order to visualize the lesion, and TURB can treat the condition. Lesions are generally low-grade and non-muscle invasive, but high-grade lesions can also be detected. In present series, after TURB, follow-up US monitoring at increasing intervals was used at all centres, follow-up cystoscopies were added in two centres, but with different schedules. Urine cytologies were considered only at one centre. After a median follow-up of 5 years (range 9 months-14.5 years), none of the patients showed recurrence or progression of the disease.	bladder